• 한국전자통신학회논문지
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• 제15권3호
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• pp.445-450
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• 2020

협력 네트워크는 전송기에서 송신기로 신호를 전송할 때 여러 개의 중계기를 통해 신호를 전송함으로써 통신성능을 향상시키고 전송용량을 증가시키는 장점을 제공한다. 본 논문에서는 송신기와 중계기 사이에서는 일반적인 이진변조방식을 이용하여 신호를 전송하고 중계기와 수신기 사이에서는 차등 공간 시간 코드 방식을 적용한 신호전송 시스템을 고려한다. 먼저 송신기와 중계기 사이에서 동기방식과 차등변조 방식을 적용했을 때의 성능을 분석한다. 변조방식 및 중계기의 개수를 고려한 다양한 중계기 위치에서의 성능 또한 비교한다.

• Spatial Information Research
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• 제13권1호
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• pp.43-53
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• 2005

본 연구에서는 폐쇄성 수역에 있어서 비점 오염원의 모델링 및 적정 수환경 관리방안에 대하여 고찰하였다 공간적으로 분포하는 각종 환경정보를 효과적으로 얻기 위하여 GIS데이터(contour data)를 이용하였다. 등고선 데이터로부터 소유역 및 하도망을 자동적으로 도출하였으며, 준 수치고도모델(Quasi Digital Elevation Model)을 모형화함으로써 유역으로부터의 질소 오염물질 유출량을 해석하였다. 본 모형은 실측자료를 토대로 유효화하였다. GIS와 연계한 본 모형은 수역의 오염현황을 고려한 유역의 비점 오염원유출 분석에 효과적이며, 향후 수 환경 관리에 적절하게 이용될 것으로 기대한다.

• 분석과학
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• 제8권4호
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• pp.487-492
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• 1995

The chemical compositions and pyrolysis characteristics of oil shales and source rocks distributed in the southwestern and southeastern parts of the Korean peninsular have been investigated. In order to compare the results of Korean samples with those of shales giving high oil yields, two Colorado oil shale samples and one Paris source rock samples were also investigated. Chemical compositions of the samples were analysed by means of gravimetry, CHN analysis, X-ray diffraction method, inductively coupled plasma atomic emission spectrometry and atomic absorption spectrometry. A custom made pyrolyser and a Rock-Eval system were used for the pyrolysis studies. Pyrolyses of the samples were carried out by means of a temperature controlling device to $600^{\circ}C$ at a heating rate of $5^{\circ}C/min$ with a helium flow rate of $1200m{\ell}/min$. The results of pyrolysis study indicated that Colorado shale samples belong to type I and all the other samples belong to type II.

• 조명전기설비학회논문지
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• 제22권5호
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• pp.53-57
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• 2008

일반적으로 비상시 전원으로 디젤발전기를 가장 많이 사용하고 있으며, 하이브리드 전원소스(상용전원, 축전지, 연료전지, 태양전지 등)를 사용하여 부하에 안정적인 전력을 공급하기 위한 방법들이 연구되어지고 있다. 최근 비상시 전원으로 가장 많이 사용하고 있는 디젤발전기의 역할이 아주 중요하게 여겨지며, 운영부하에 따라서도 유연하게 동작되어야 하고, 신뢰성도 확보되어야 한다. 따라서 본 연구에서 부하 변동에 따른 최대전력 추종제어 기능이 가능하고, 고조파 억제 기능 및 안정주파수 유지기능이 가능하도록 부하 변동에 따른 디젤발전기의 제어기에 대하여 논하고자 한다.

• 지식경영연구
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• 제9권4호
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• pp.17-33
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• 2008

This study proposes University 2.0 as a model case of open, flexible, and distributed learning environment for higher education based on theoretical foundations and perspectives. As web 2.0 technologies emerge into the field of education, ways of generating and disseminating information and knowledge have been drastically changed. Professors are no longer the only source of knowledge. Students using internet often become prosumers of knowledge who search and access information through the web as well as publish their own knowledge using the web. A concept and framework of University 2.0 is introduced for implementing the new interactive learning paradigm with an open, flexible and distributed learning environment for higher education. University 2.0 incorporates online and offline learning environments with various educational media. Furthermore, it employs various learning strategies and integrates formal and informal learning through learning communities. Both instructors and students in University 2.0 environment are expected to be active knowledge generators as well as creative designers of their own learning and teaching.

• 전기학회논문지
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• 제57권10호
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• pp.1744-1751
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• 2008

This paper presents a monitor positioning algorithm to identify the power quality event source in the distribution system with distributed generations. This algorithm determines the appropriate number of monitors and their locations considering power system topology together with distributed generation. This paper summarizes the guidelines of monitor positioning into five principles and defines the weighting factors according to the principles. To evaluate the adequacy of monitor positioning results, ambiguity indices considering monitor location and system topology are proposed. The optimal number and locations of monitors are determined from optimization routine using the weighting factors and the monitor positioning results are evaluated in terms of ambiguity indices. The algorithm is applied to IEEE 13 bus test feeder and suggests the optimal number and locations of power quality monitors. The proposed approach can realize the expert's knowledge on monitor positioning into a sophisticated automatic computing algorithm.

• Journal of information and communication convergence engineering
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• 제13권3호
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• pp.152-158
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• 2015

We consider the problem of designing independently operating local quantizers at nodes in distributed estimation systems, where many spatially distributed sensor nodes measure a parameter of interest, quantize these measurements, and send the quantized data to a fusion node, which conducts the parameter estimation. Motivated by the discussion that the estimation accuracy can be improved by using the quantized data with a high probability of occurrence, we propose an iterative algorithm with a simple design rule that produces quantizers by searching boundary values with an increased likelihood. We prove that this design rule generates a considerably reduced interval for finding the next boundary values, yielding a low design complexity. We demonstrate through extensive simulations that the proposed algorithm achieves a significant performance gain with respect to traditional quantizer designs. A comparison with the recently published novel algorithms further illustrates the benefit of the proposed technique in terms of performance and design complexity.

• Journal of information and communication convergence engineering
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• 제14권4호
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• pp.215-221
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• 2016

We consider a design of a combined quantizer and estimator for distributed systems wherein each node quantizes its measurement without any communication among the nodes and transmits it to a fusion node for estimation. Noting that the quantization partitions minimizing the estimation error are not independently encoded at nodes, we focus on the parameter regions created by the partitions and propose a cluster-based quantization algorithm that iteratively finds a given number of clusters of parameter regions with each region being closer to the corresponding codeword than to the other codewords. We introduce a new metric to determine the distance between codewords and parameter regions. We also discuss that the fusion node can perform an efficient estimation by finding the intersection of the clusters sent from the nodes. We demonstrate through experiments that the proposed design achieves a significant performance gain with a low complexity as compared to the previous designs.

• Journal of Electrical Engineering and Technology
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• 제8권2호
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• pp.223-229
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• 2013

Restructuring and recent developments in the power system and problems arising from construction and maintenance of large power plants, increasing amount of interest in distributed generation (DG) source. Distributed generation units due to specifications, technology and location network connectivity can improve system and load point reliability indices. In this paper, the allocation and sizing of DG in distribution networks are determined using optimization. The objective function of the proposed method is to improve customer-based reliability indices at lowest cost. The placement and size of DGs are optimized using a Genetic Algorithm (GA). To evaluate the proposed algorithm, 34-bus IEEE test system, is used. The results illustrate efficiency of the proposed method.

• 대한의용생체공학회:의공학회지
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• 제15권1호
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• pp.105-110
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• 1994

In this paper, we present a method to evaluate source locations and distributed region which is specified brain activity, as indicated by locations and strengths of intracranial sources, using potential gradients of interpolation polynomials and topographic mapping of the EEG records. This method can analyze the variance of source temporally or spatially and leads to enable a quantitative evaluation of potential gradients drawing methods which is now being used in the clinic. In the result, we obtained the overall potentials distribution on the entire scalp and the information of potential source locations from the EEG records of a patient which was known to epilepsy.